2003-02-23 07:57:48 +08:00
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//===- Mem2Reg.cpp - The -mem2reg pass, a wrapper around the Utils lib ----===//
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2005-04-22 07:48:37 +08:00
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//
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2003-10-21 03:43:21 +08:00
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// The LLVM Compiler Infrastructure
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//
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2007-12-30 04:36:04 +08:00
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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2005-04-22 07:48:37 +08:00
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//
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2003-10-21 03:43:21 +08:00
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//===----------------------------------------------------------------------===//
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2003-02-23 07:57:48 +08:00
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//
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// This pass is a simple pass wrapper around the PromoteMemToReg function call
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// exposed by the Utils library.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar.h"
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2012-12-04 00:50:05 +08:00
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#include "llvm/ADT/Statistic.h"
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Make use of @llvm.assume in ValueTracking (computeKnownBits, etc.)
This change, which allows @llvm.assume to be used from within computeKnownBits
(and other associated functions in ValueTracking), adds some (optional)
parameters to computeKnownBits and friends. These functions now (optionally)
take a "context" instruction pointer, an AssumptionTracker pointer, and also a
DomTree pointer, and most of the changes are just to pass this new information
when it is easily available from InstSimplify, InstCombine, etc.
As explained below, the significant conceptual change is that known properties
of a value might depend on the control-flow location of the use (because we
care that the @llvm.assume dominates the use because assumptions have
control-flow dependencies). This means that, when we ask if bits are known in a
value, we might get different answers for different uses.
The significant changes are all in ValueTracking. Two main changes: First, as
with the rest of the code, new parameters need to be passed around. To make
this easier, I grouped them into a structure, and I made internal static
versions of the relevant functions that take this structure as a parameter. The
new code does as you might expect, it looks for @llvm.assume calls that make
use of the value we're trying to learn something about (often indirectly),
attempts to pattern match that expression, and uses the result if successful.
By making use of the AssumptionTracker, the process of finding @llvm.assume
calls is not expensive.
Part of the structure being passed around inside ValueTracking is a set of
already-considered @llvm.assume calls. This is to prevent a query using, for
example, the assume(a == b), to recurse on itself. The context and DT params
are used to find applicable assumptions. An assumption needs to dominate the
context instruction, or come after it deterministically. In this latter case we
only handle the specific case where both the assumption and the context
instruction are in the same block, and we need to exclude assumptions from
being used to simplify their own ephemeral values (those which contribute only
to the assumption) because otherwise the assumption would prove its feeding
comparison trivial and would be removed.
This commit adds the plumbing and the logic for a simple masked-bit propagation
(just enough to write a regression test). Future commits add more patterns
(and, correspondingly, more regression tests).
llvm-svn: 217342
2014-09-08 02:57:58 +08:00
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#include "llvm/Analysis/AssumptionTracker.h"
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2014-01-13 17:26:24 +08:00
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#include "llvm/IR/Dominators.h"
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2013-01-02 19:36:10 +08:00
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#include "llvm/IR/Function.h"
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#include "llvm/IR/Instructions.h"
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2012-12-04 00:50:05 +08:00
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#include "llvm/Transforms/Utils/PromoteMemToReg.h"
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#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
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2004-01-09 14:02:20 +08:00
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using namespace llvm;
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2003-11-12 06:41:34 +08:00
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2014-04-22 10:55:47 +08:00
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#define DEBUG_TYPE "mem2reg"
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2006-12-20 06:17:40 +08:00
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STATISTIC(NumPromoted, "Number of alloca's promoted");
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2003-02-23 07:57:48 +08:00
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2006-12-20 06:17:40 +08:00
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namespace {
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2009-10-25 14:33:48 +08:00
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struct PromotePass : public FunctionPass {
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2007-05-06 21:37:16 +08:00
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static char ID; // Pass identification, replacement for typeid
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2010-10-20 01:21:58 +08:00
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PromotePass() : FunctionPass(ID) {
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initializePromotePassPass(*PassRegistry::getPassRegistry());
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}
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2007-05-02 05:15:47 +08:00
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2003-02-23 07:57:48 +08:00
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// runOnFunction - To run this pass, first we calculate the alloca
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// instructions that are safe for promotion, then we promote each one.
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//
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2014-03-05 17:10:37 +08:00
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bool runOnFunction(Function &F) override;
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2003-02-23 07:57:48 +08:00
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2014-03-05 17:10:37 +08:00
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void getAnalysisUsage(AnalysisUsage &AU) const override {
|
Make use of @llvm.assume in ValueTracking (computeKnownBits, etc.)
This change, which allows @llvm.assume to be used from within computeKnownBits
(and other associated functions in ValueTracking), adds some (optional)
parameters to computeKnownBits and friends. These functions now (optionally)
take a "context" instruction pointer, an AssumptionTracker pointer, and also a
DomTree pointer, and most of the changes are just to pass this new information
when it is easily available from InstSimplify, InstCombine, etc.
As explained below, the significant conceptual change is that known properties
of a value might depend on the control-flow location of the use (because we
care that the @llvm.assume dominates the use because assumptions have
control-flow dependencies). This means that, when we ask if bits are known in a
value, we might get different answers for different uses.
The significant changes are all in ValueTracking. Two main changes: First, as
with the rest of the code, new parameters need to be passed around. To make
this easier, I grouped them into a structure, and I made internal static
versions of the relevant functions that take this structure as a parameter. The
new code does as you might expect, it looks for @llvm.assume calls that make
use of the value we're trying to learn something about (often indirectly),
attempts to pattern match that expression, and uses the result if successful.
By making use of the AssumptionTracker, the process of finding @llvm.assume
calls is not expensive.
Part of the structure being passed around inside ValueTracking is a set of
already-considered @llvm.assume calls. This is to prevent a query using, for
example, the assume(a == b), to recurse on itself. The context and DT params
are used to find applicable assumptions. An assumption needs to dominate the
context instruction, or come after it deterministically. In this latter case we
only handle the specific case where both the assumption and the context
instruction are in the same block, and we need to exclude assumptions from
being used to simplify their own ephemeral values (those which contribute only
to the assumption) because otherwise the assumption would prove its feeding
comparison trivial and would be removed.
This commit adds the plumbing and the logic for a simple masked-bit propagation
(just enough to write a regression test). Future commits add more patterns
(and, correspondingly, more regression tests).
llvm-svn: 217342
2014-09-08 02:57:58 +08:00
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AU.addRequired<AssumptionTracker>();
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2014-01-13 21:07:17 +08:00
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AU.addRequired<DominatorTreeWrapperPass>();
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2003-02-23 07:57:48 +08:00
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AU.setPreservesCFG();
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2007-04-17 02:10:23 +08:00
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// This is a cluster of orthogonal Transforms
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2006-05-09 12:13:41 +08:00
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AU.addPreserved<UnifyFunctionExitNodes>();
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AU.addPreservedID(LowerSwitchID);
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2006-05-18 05:05:27 +08:00
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AU.addPreservedID(LowerInvokePassID);
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2003-02-23 07:57:48 +08:00
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}
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};
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} // end of anonymous namespace
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2008-05-13 08:00:25 +08:00
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char PromotePass::ID = 0;
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2010-10-13 03:48:12 +08:00
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INITIALIZE_PASS_BEGIN(PromotePass, "mem2reg", "Promote Memory to Register",
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false, false)
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Make use of @llvm.assume in ValueTracking (computeKnownBits, etc.)
This change, which allows @llvm.assume to be used from within computeKnownBits
(and other associated functions in ValueTracking), adds some (optional)
parameters to computeKnownBits and friends. These functions now (optionally)
take a "context" instruction pointer, an AssumptionTracker pointer, and also a
DomTree pointer, and most of the changes are just to pass this new information
when it is easily available from InstSimplify, InstCombine, etc.
As explained below, the significant conceptual change is that known properties
of a value might depend on the control-flow location of the use (because we
care that the @llvm.assume dominates the use because assumptions have
control-flow dependencies). This means that, when we ask if bits are known in a
value, we might get different answers for different uses.
The significant changes are all in ValueTracking. Two main changes: First, as
with the rest of the code, new parameters need to be passed around. To make
this easier, I grouped them into a structure, and I made internal static
versions of the relevant functions that take this structure as a parameter. The
new code does as you might expect, it looks for @llvm.assume calls that make
use of the value we're trying to learn something about (often indirectly),
attempts to pattern match that expression, and uses the result if successful.
By making use of the AssumptionTracker, the process of finding @llvm.assume
calls is not expensive.
Part of the structure being passed around inside ValueTracking is a set of
already-considered @llvm.assume calls. This is to prevent a query using, for
example, the assume(a == b), to recurse on itself. The context and DT params
are used to find applicable assumptions. An assumption needs to dominate the
context instruction, or come after it deterministically. In this latter case we
only handle the specific case where both the assumption and the context
instruction are in the same block, and we need to exclude assumptions from
being used to simplify their own ephemeral values (those which contribute only
to the assumption) because otherwise the assumption would prove its feeding
comparison trivial and would be removed.
This commit adds the plumbing and the logic for a simple masked-bit propagation
(just enough to write a regression test). Future commits add more patterns
(and, correspondingly, more regression tests).
llvm-svn: 217342
2014-09-08 02:57:58 +08:00
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INITIALIZE_PASS_DEPENDENCY(AssumptionTracker)
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2014-01-13 21:07:17 +08:00
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INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
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2010-10-13 03:48:12 +08:00
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INITIALIZE_PASS_END(PromotePass, "mem2reg", "Promote Memory to Register",
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2010-10-08 06:25:06 +08:00
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false, false)
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2008-05-13 08:00:25 +08:00
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2003-02-23 07:57:48 +08:00
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bool PromotePass::runOnFunction(Function &F) {
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std::vector<AllocaInst*> Allocas;
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2003-09-20 22:39:18 +08:00
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BasicBlock &BB = F.getEntryBlock(); // Get the entry node for the function
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2003-02-23 07:57:48 +08:00
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2003-06-25 22:58:56 +08:00
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bool Changed = false;
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2003-10-06 05:20:13 +08:00
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2014-01-13 21:07:17 +08:00
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DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
|
Make use of @llvm.assume in ValueTracking (computeKnownBits, etc.)
This change, which allows @llvm.assume to be used from within computeKnownBits
(and other associated functions in ValueTracking), adds some (optional)
parameters to computeKnownBits and friends. These functions now (optionally)
take a "context" instruction pointer, an AssumptionTracker pointer, and also a
DomTree pointer, and most of the changes are just to pass this new information
when it is easily available from InstSimplify, InstCombine, etc.
As explained below, the significant conceptual change is that known properties
of a value might depend on the control-flow location of the use (because we
care that the @llvm.assume dominates the use because assumptions have
control-flow dependencies). This means that, when we ask if bits are known in a
value, we might get different answers for different uses.
The significant changes are all in ValueTracking. Two main changes: First, as
with the rest of the code, new parameters need to be passed around. To make
this easier, I grouped them into a structure, and I made internal static
versions of the relevant functions that take this structure as a parameter. The
new code does as you might expect, it looks for @llvm.assume calls that make
use of the value we're trying to learn something about (often indirectly),
attempts to pattern match that expression, and uses the result if successful.
By making use of the AssumptionTracker, the process of finding @llvm.assume
calls is not expensive.
Part of the structure being passed around inside ValueTracking is a set of
already-considered @llvm.assume calls. This is to prevent a query using, for
example, the assume(a == b), to recurse on itself. The context and DT params
are used to find applicable assumptions. An assumption needs to dominate the
context instruction, or come after it deterministically. In this latter case we
only handle the specific case where both the assumption and the context
instruction are in the same block, and we need to exclude assumptions from
being used to simplify their own ephemeral values (those which contribute only
to the assumption) because otherwise the assumption would prove its feeding
comparison trivial and would be removed.
This commit adds the plumbing and the logic for a simple masked-bit propagation
(just enough to write a regression test). Future commits add more patterns
(and, correspondingly, more regression tests).
llvm-svn: 217342
2014-09-08 02:57:58 +08:00
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AssumptionTracker *AT = &getAnalysis<AssumptionTracker>();
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2005-04-22 07:48:37 +08:00
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2003-06-25 22:58:56 +08:00
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while (1) {
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Allocas.clear();
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// Find allocas that are safe to promote, by looking at all instructions in
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// the entry node
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for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I)
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if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) // Is it an alloca?
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2013-08-14 06:51:58 +08:00
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if (isAllocaPromotable(AI))
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2003-06-25 22:58:56 +08:00
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Allocas.push_back(AI);
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if (Allocas.empty()) break;
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Make use of @llvm.assume in ValueTracking (computeKnownBits, etc.)
This change, which allows @llvm.assume to be used from within computeKnownBits
(and other associated functions in ValueTracking), adds some (optional)
parameters to computeKnownBits and friends. These functions now (optionally)
take a "context" instruction pointer, an AssumptionTracker pointer, and also a
DomTree pointer, and most of the changes are just to pass this new information
when it is easily available from InstSimplify, InstCombine, etc.
As explained below, the significant conceptual change is that known properties
of a value might depend on the control-flow location of the use (because we
care that the @llvm.assume dominates the use because assumptions have
control-flow dependencies). This means that, when we ask if bits are known in a
value, we might get different answers for different uses.
The significant changes are all in ValueTracking. Two main changes: First, as
with the rest of the code, new parameters need to be passed around. To make
this easier, I grouped them into a structure, and I made internal static
versions of the relevant functions that take this structure as a parameter. The
new code does as you might expect, it looks for @llvm.assume calls that make
use of the value we're trying to learn something about (often indirectly),
attempts to pattern match that expression, and uses the result if successful.
By making use of the AssumptionTracker, the process of finding @llvm.assume
calls is not expensive.
Part of the structure being passed around inside ValueTracking is a set of
already-considered @llvm.assume calls. This is to prevent a query using, for
example, the assume(a == b), to recurse on itself. The context and DT params
are used to find applicable assumptions. An assumption needs to dominate the
context instruction, or come after it deterministically. In this latter case we
only handle the specific case where both the assumption and the context
instruction are in the same block, and we need to exclude assumptions from
being used to simplify their own ephemeral values (those which contribute only
to the assumption) because otherwise the assumption would prove its feeding
comparison trivial and would be removed.
This commit adds the plumbing and the logic for a simple masked-bit propagation
(just enough to write a regression test). Future commits add more patterns
(and, correspondingly, more regression tests).
llvm-svn: 217342
2014-09-08 02:57:58 +08:00
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PromoteMemToReg(Allocas, DT, nullptr, AT);
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2003-02-23 07:57:48 +08:00
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NumPromoted += Allocas.size();
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2003-06-25 22:58:56 +08:00
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Changed = true;
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2003-02-23 07:57:48 +08:00
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}
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2003-06-25 22:58:56 +08:00
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return Changed;
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2003-02-23 07:57:48 +08:00
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}
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// createPromoteMemoryToRegister - Provide an entry point to create this pass.
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//
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2005-03-28 10:01:12 +08:00
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FunctionPass *llvm::createPromoteMemoryToRegisterPass() {
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2003-02-23 07:57:48 +08:00
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return new PromotePass();
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}
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